Mummification

If you're into heavier bondage, there aren't many ways to get closer to immobilization than mummification. There are a few mediums like vet wrap, duct tape, seran wrap, or pallet wrap you commonly see used but occasionally you'll see interesting variants to get the same result like an inflatable mattress wrapped around someone, sleeping bags, or in a box with foam. The only part better than the immobilization itself is when the only part of your body that can experience the world outside your cocoon is your cock and/or nipples.

A few random pointers for anyone looking to try this out: 

Safety scissors will make removing the wrappings significantly easier than using typical scissors.

If you're using seran wrap or anything that is self-adhesive, wrap the boys arms in it separately before wrapping his body. Basically this functions like the internal sleeves in sleepsacks and will keep his arms in place so he can't bring them to the front of his body.

Keep cotton balls or something disposable handy to put over the boy's nipples while wrapping. Otherwise you may have a hard time only grabbing the wrapping and not also his skin.

When using both seran wrap and duct tape for full enclosure (as opposed to just bands), be sure you only pull with the seran wrap. The seran wrap has more give than the duct tape, so if you pull it it will be more likely to cut off circulation. Instead, just lay it on top; it will still give the extra added strength.